Have people ever been more excited about superheroes? Over the last few years, the comic-book fervor has only grown, so that now it doesn’t feel like summer if you don’t see someone in a cape at the cinema, and Marvel’s Agents of S.H.I.E.L.D. is one of the most talked-about TV shows of the season.

A new documentary, Superheroes: A Never-Ending Battle, premieres tonight at 8pm on PBS, and it seeks to answer why caped crusaders are having such a moment. We chatted with director Michael Kantor to get a little preview.

The documentary features appearances from Spiderman creator Stan Lee, original Batman star Adam West, original Wonder Woman Lynda Carter, Pulitzer-Prize winner Michael Chabon, and loads of writers, artists, and executives at Marvel Entertainment and DC Comics. “We tried to focus, because it is a huge history, on the key moments in the evolution of superheroes,” Kantor explains.

The doc is in three parts.

“The first part covers really the origin of a number of superheroes including Superman, Wonder Woman, Captain America, and goes from the 1930s until the late 1950s,” says Kantor. “The second one goes from 1959-1977 and covers the creation of the Marvel universe. The third one is the modern era in superheroes, beginning with the Superman movie in the late 70s.”

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Superhero creators admitted when they’ve copied someone else.

Joe Simon, who co-created Captain America and has since passed away, mentioned in the film that the way in which the character gets injected with a serum and gains powers was stolen right from the character of the Blue Beetle: “If something works, you use it eight times.”

How is Thor’s hammer that heavy, anyway? Could gamma rays really turn a person into the Hulk? No matter how silly, it’s essential fan viewing to see some sort of biological basis for these cool ideas.

Turns out, comic books aren’t just for boys.

The doc features Jennette Kahn, who was only 28 when she became the publisher, and eventually President, of DC Comics. She wound up running things for 26 years. “She was really good about talking about how the industry stopped being such a boys’ club,” says Kantor.

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The filmmakers have a theory about why we love superheroes so much.

“Superheroes flourish when we are particularly fearful of something,” Kantor explains. “In the Great Depression, we were worried about putting food on the table; in the ’60s, the anxieties of the atomic age; and now with terrorism we are looking for these ideas that can reassure us that everything is going to be okay.” Maybe that’s why S.H.I.E.L.D. is doing so well? The Avengers could help the government shutdown, definitely.